blob: 64acd05f71c8743330e47a1d9883fc59acc22081 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/drivers/char/raw.c
3 *
4 * Front-end raw character devices. These can be bound to any block
5 * devices to provide genuine Unix raw character device semantics.
6 *
7 * We reserve minor number 0 for a control interface. ioctl()s on this
8 * device are used to bind the other minor numbers to block devices.
9 */
10
11#include <linux/init.h>
12#include <linux/fs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070013#include <linux/major.h>
14#include <linux/blkdev.h>
15#include <linux/module.h>
16#include <linux/raw.h>
17#include <linux/capability.h>
18#include <linux/uio.h>
19#include <linux/cdev.h>
20#include <linux/device.h>
Arjan van de Ven8ed965d2006-03-23 03:00:21 -080021#include <linux/mutex.h>
Jonathan Corbetc0bed682008-05-16 13:54:46 -060022#include <linux/smp_lock.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070023
24#include <asm/uaccess.h>
25
26struct raw_device_data {
27 struct block_device *binding;
28 int inuse;
29};
30
gregkh@suse.deca8eca62005-03-23 09:53:09 -080031static struct class *raw_class;
Linus Torvalds1da177e2005-04-16 15:20:36 -070032static struct raw_device_data raw_devices[MAX_RAW_MINORS];
Arjan van de Ven8ed965d2006-03-23 03:00:21 -080033static DEFINE_MUTEX(raw_mutex);
Arjan van de Ven62322d22006-07-03 00:24:21 -070034static const struct file_operations raw_ctl_fops; /* forward declaration */
Linus Torvalds1da177e2005-04-16 15:20:36 -070035
36/*
37 * Open/close code for raw IO.
38 *
39 * We just rewrite the i_mapping for the /dev/raw/rawN file descriptor to
40 * point at the blockdev's address_space and set the file handle to use
41 * O_DIRECT.
42 *
43 * Set the device's soft blocksize to the minimum possible. This gives the
44 * finest possible alignment and has no adverse impact on performance.
45 */
46static int raw_open(struct inode *inode, struct file *filp)
47{
48 const int minor = iminor(inode);
49 struct block_device *bdev;
50 int err;
51
52 if (minor == 0) { /* It is the control device */
53 filp->f_op = &raw_ctl_fops;
54 return 0;
55 }
56
Jonathan Corbetc0bed682008-05-16 13:54:46 -060057 lock_kernel();
Arjan van de Ven8ed965d2006-03-23 03:00:21 -080058 mutex_lock(&raw_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070059
60 /*
61 * All we need to do on open is check that the device is bound.
62 */
63 bdev = raw_devices[minor].binding;
64 err = -ENODEV;
65 if (!bdev)
66 goto out;
67 igrab(bdev->bd_inode);
Al Viro572c4892007-10-08 13:24:05 -040068 err = blkdev_get(bdev, filp->f_mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -070069 if (err)
70 goto out;
71 err = bd_claim(bdev, raw_open);
72 if (err)
73 goto out1;
Martin K. Petersene1defc42009-05-22 17:17:49 -040074 err = set_blocksize(bdev, bdev_logical_block_size(bdev));
Linus Torvalds1da177e2005-04-16 15:20:36 -070075 if (err)
76 goto out2;
77 filp->f_flags |= O_DIRECT;
78 filp->f_mapping = bdev->bd_inode->i_mapping;
79 if (++raw_devices[minor].inuse == 1)
Josef Sipeka7113a92006-12-08 02:36:55 -080080 filp->f_path.dentry->d_inode->i_mapping =
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 bdev->bd_inode->i_mapping;
82 filp->private_data = bdev;
Arjan van de Ven8ed965d2006-03-23 03:00:21 -080083 mutex_unlock(&raw_mutex);
Jonathan Corbetc0bed682008-05-16 13:54:46 -060084 unlock_kernel();
Linus Torvalds1da177e2005-04-16 15:20:36 -070085 return 0;
86
87out2:
88 bd_release(bdev);
89out1:
Al Viro9a1c3542008-02-22 20:40:24 -050090 blkdev_put(bdev, filp->f_mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -070091out:
Arjan van de Ven8ed965d2006-03-23 03:00:21 -080092 mutex_unlock(&raw_mutex);
Dan Carpenter996ff682009-03-27 13:28:48 +030093 unlock_kernel();
Linus Torvalds1da177e2005-04-16 15:20:36 -070094 return err;
95}
96
97/*
98 * When the final fd which refers to this character-special node is closed, we
99 * make its ->mapping point back at its own i_data.
100 */
101static int raw_release(struct inode *inode, struct file *filp)
102{
103 const int minor= iminor(inode);
104 struct block_device *bdev;
105
Arjan van de Ven8ed965d2006-03-23 03:00:21 -0800106 mutex_lock(&raw_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107 bdev = raw_devices[minor].binding;
108 if (--raw_devices[minor].inuse == 0) {
109 /* Here inode->i_mapping == bdev->bd_inode->i_mapping */
110 inode->i_mapping = &inode->i_data;
111 inode->i_mapping->backing_dev_info = &default_backing_dev_info;
112 }
Arjan van de Ven8ed965d2006-03-23 03:00:21 -0800113 mutex_unlock(&raw_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114
115 bd_release(bdev);
Al Viro9a1c3542008-02-22 20:40:24 -0500116 blkdev_put(bdev, filp->f_mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 return 0;
118}
119
120/*
121 * Forward ioctls to the underlying block device.
122 */
123static int
124raw_ioctl(struct inode *inode, struct file *filp,
125 unsigned int command, unsigned long arg)
126{
127 struct block_device *bdev = filp->private_data;
128
Al Viro56b26ad2008-09-19 03:17:36 -0400129 return blkdev_ioctl(bdev, 0, command, arg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130}
131
132static void bind_device(struct raw_config_request *rq)
133{
Greg Kroah-Hartman38ca6c32006-08-07 22:19:37 -0700134 device_destroy(raw_class, MKDEV(RAW_MAJOR, rq->raw_minor));
Greg Kroah-Hartman03457cd2008-07-21 20:03:34 -0700135 device_create(raw_class, NULL, MKDEV(RAW_MAJOR, rq->raw_minor), NULL,
136 "raw%d", rq->raw_minor);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137}
138
139/*
140 * Deal with ioctls against the raw-device control interface, to bind
141 * and unbind other raw devices.
142 */
143static int raw_ctl_ioctl(struct inode *inode, struct file *filp,
144 unsigned int command, unsigned long arg)
145{
146 struct raw_config_request rq;
147 struct raw_device_data *rawdev;
148 int err = 0;
149
150 switch (command) {
151 case RAW_SETBIND:
152 case RAW_GETBIND:
153
154 /* First, find out which raw minor we want */
155
156 if (copy_from_user(&rq, (void __user *) arg, sizeof(rq))) {
157 err = -EFAULT;
158 goto out;
159 }
160
Jeff Moyer38584c12007-02-10 01:46:10 -0800161 if (rq.raw_minor <= 0 || rq.raw_minor >= MAX_RAW_MINORS) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162 err = -EINVAL;
163 goto out;
164 }
165 rawdev = &raw_devices[rq.raw_minor];
166
167 if (command == RAW_SETBIND) {
168 dev_t dev;
169
170 /*
171 * This is like making block devices, so demand the
172 * same capability
173 */
174 if (!capable(CAP_SYS_ADMIN)) {
175 err = -EPERM;
176 goto out;
177 }
178
179 /*
180 * For now, we don't need to check that the underlying
181 * block device is present or not: we can do that when
182 * the raw device is opened. Just check that the
183 * major/minor numbers make sense.
184 */
185
186 dev = MKDEV(rq.block_major, rq.block_minor);
187 if ((rq.block_major == 0 && rq.block_minor != 0) ||
188 MAJOR(dev) != rq.block_major ||
189 MINOR(dev) != rq.block_minor) {
190 err = -EINVAL;
191 goto out;
192 }
193
Arjan van de Ven8ed965d2006-03-23 03:00:21 -0800194 mutex_lock(&raw_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195 if (rawdev->inuse) {
Arjan van de Ven8ed965d2006-03-23 03:00:21 -0800196 mutex_unlock(&raw_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197 err = -EBUSY;
198 goto out;
199 }
200 if (rawdev->binding) {
201 bdput(rawdev->binding);
202 module_put(THIS_MODULE);
203 }
204 if (rq.block_major == 0 && rq.block_minor == 0) {
205 /* unbind */
206 rawdev->binding = NULL;
Greg Kroah-Hartman38ca6c32006-08-07 22:19:37 -0700207 device_destroy(raw_class,
gregkh@suse.deca8eca62005-03-23 09:53:09 -0800208 MKDEV(RAW_MAJOR, rq.raw_minor));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209 } else {
210 rawdev->binding = bdget(dev);
211 if (rawdev->binding == NULL)
212 err = -ENOMEM;
213 else {
214 __module_get(THIS_MODULE);
215 bind_device(&rq);
216 }
217 }
Arjan van de Ven8ed965d2006-03-23 03:00:21 -0800218 mutex_unlock(&raw_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219 } else {
220 struct block_device *bdev;
221
Arjan van de Ven8ed965d2006-03-23 03:00:21 -0800222 mutex_lock(&raw_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223 bdev = rawdev->binding;
224 if (bdev) {
225 rq.block_major = MAJOR(bdev->bd_dev);
226 rq.block_minor = MINOR(bdev->bd_dev);
227 } else {
228 rq.block_major = rq.block_minor = 0;
229 }
Arjan van de Ven8ed965d2006-03-23 03:00:21 -0800230 mutex_unlock(&raw_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231 if (copy_to_user((void __user *)arg, &rq, sizeof(rq))) {
232 err = -EFAULT;
233 goto out;
234 }
235 }
236 break;
237 default:
238 err = -EINVAL;
239 break;
240 }
241out:
242 return err;
243}
244
Arjan van de Ven62322d22006-07-03 00:24:21 -0700245static const struct file_operations raw_fops = {
Badari Pulavarty543ade12006-09-30 23:28:48 -0700246 .read = do_sync_read,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247 .aio_read = generic_file_aio_read,
Badari Pulavarty543ade12006-09-30 23:28:48 -0700248 .write = do_sync_write,
Christoph Hellwigeef99382009-08-20 17:43:41 +0200249 .aio_write = blkdev_aio_write,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250 .open = raw_open,
251 .release= raw_release,
252 .ioctl = raw_ioctl,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253 .owner = THIS_MODULE,
254};
255
Arjan van de Ven62322d22006-07-03 00:24:21 -0700256static const struct file_operations raw_ctl_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257 .ioctl = raw_ctl_ioctl,
258 .open = raw_open,
259 .owner = THIS_MODULE,
260};
261
Greg Kroah-Hartman7e7654a2007-09-12 15:06:57 -0700262static struct cdev raw_cdev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263
Kay Sieverse454cea2009-09-18 23:01:12 +0200264static char *raw_devnode(struct device *dev, mode_t *mode)
Kay Sievers6fd46932009-04-30 15:23:42 +0200265{
266 return kasprintf(GFP_KERNEL, "raw/%s", dev_name(dev));
267}
268
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269static int __init raw_init(void)
270{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271 dev_t dev = MKDEV(RAW_MAJOR, 0);
Rolf Eike Beer3e26a422006-09-29 02:00:46 -0700272 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273
Rolf Eike Beer3e26a422006-09-29 02:00:46 -0700274 ret = register_chrdev_region(dev, MAX_RAW_MINORS, "raw");
275 if (ret)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276 goto error;
277
278 cdev_init(&raw_cdev, &raw_fops);
Rolf Eike Beer3e26a422006-09-29 02:00:46 -0700279 ret = cdev_add(&raw_cdev, dev, MAX_RAW_MINORS);
280 if (ret) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281 kobject_put(&raw_cdev.kobj);
Rolf Eike Beer3e26a422006-09-29 02:00:46 -0700282 goto error_region;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283 }
284
gregkh@suse.deca8eca62005-03-23 09:53:09 -0800285 raw_class = class_create(THIS_MODULE, "raw");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286 if (IS_ERR(raw_class)) {
287 printk(KERN_ERR "Error creating raw class.\n");
288 cdev_del(&raw_cdev);
Rolf Eike Beer3e26a422006-09-29 02:00:46 -0700289 ret = PTR_ERR(raw_class);
290 goto error_region;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291 }
Kay Sieverse454cea2009-09-18 23:01:12 +0200292 raw_class->devnode = raw_devnode;
Greg Kroah-Hartman03457cd2008-07-21 20:03:34 -0700293 device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), NULL, "rawctl");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295 return 0;
296
Rolf Eike Beer3e26a422006-09-29 02:00:46 -0700297error_region:
298 unregister_chrdev_region(dev, MAX_RAW_MINORS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299error:
Rolf Eike Beer3e26a422006-09-29 02:00:46 -0700300 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301}
302
303static void __exit raw_exit(void)
304{
Greg Kroah-Hartman38ca6c32006-08-07 22:19:37 -0700305 device_destroy(raw_class, MKDEV(RAW_MAJOR, 0));
gregkh@suse.deca8eca62005-03-23 09:53:09 -0800306 class_destroy(raw_class);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307 cdev_del(&raw_cdev);
308 unregister_chrdev_region(MKDEV(RAW_MAJOR, 0), MAX_RAW_MINORS);
309}
310
311module_init(raw_init);
312module_exit(raw_exit);
313MODULE_LICENSE("GPL");